Why give something up for Lent?

I gave up sweets for Lent...again. The first few days the cravings for sugar were almost unbearable. I had a headache. I was tired without my sugar highs. I would look at my children's frosted mini wheats (which I never buy, but they talked me into the strawberry ones that were on sale) longingly.
I don't have to give something up. I never did in my younger years. My church doesn't mandate it. Somehow me thinking about sweets and making a conscious choice not to eat them makes it more real to me that at any moment when Christ was being spit at, or beaten, or hanging on that cross...at any moment he could have stopped it all. But He didn't. He didn't so my sin doesn't need to control me anymore.
I want to crave God the way I crave sweets. I want to feel weak and unable to go on if I havent spent time with Him today. I want Him to truly be my bread of life.